To upgrade your electrum with your funds intact,
you just have to copy the wallet file from
C:\Users\(username)\Desktop\electrum_data\wallets\(name of your wallet) to a temporary safe place.
[I assume the this is where your portable version's wallet file was]
Yes, that is the place it is.
That was the wallet file, that's all you need to transfer your wallet (aside from the seed).
You can put this wherever you want, you can browse it's location in the electrum "Open" menu.
Then proceed with upgrading to a 3.05 (Uninstall the old version if you're paranoid),
Open the new v3.05 Electrum (whatever the variant) and open->find your wallet file.
I think it is here I am drowning in an inch of water.....How do I have to run the installation? do I have to select 'I already have a seed'? 'Use public key'?
Do I have to do the same on both off-line and on-line (watch-only) pcs? And what else to close the loop?
Thank you all